block/replication.c

   1 /*
   2  * Replication Block filter
   3  *
   4  * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
   5  * Copyright (c) 2016 Intel Corporation
   6  * Copyright (c) 2016 FUJITSU LIMITED
   7  *
   8  * Author:
   9  *   Wen Congyang <wency@cn.fujitsu.com>
  10  *
  11  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  12  * See the COPYING file in the top-level directory.
  13  */
  14
  15 #include "qemu/osdep.h"
  16 #include "qemu-common.h"
  17 #include "block/nbd.h"
  18 #include "block/blockjob.h"
  19 #include "block/block_int.h"
  20 #include "block/block_backup.h"
  21 #include "sysemu/block-backend.h"
  22 #include "qapi/error.h"
  23 #include "replication.h"
  24
  25 typedef struct BDRVReplicationState {
  26     ReplicationMode mode;
  27     int replication_state;
  28     BdrvChild *active_disk;
  29     BdrvChild *hidden_disk;
  30     BdrvChild *secondary_disk;
  31     char *top_id;
  32     ReplicationState *rs;
  33     Error *blocker;
  34     int orig_hidden_flags;
  35     int orig_secondary_flags;
  36     int error;
  37 } BDRVReplicationState;
  38
  39 enum {
  40     BLOCK_REPLICATION_NONE,             /* block replication is not started */
  41     BLOCK_REPLICATION_RUNNING,          /* block replication is running */
  42     BLOCK_REPLICATION_FAILOVER,         /* failover is running in background */
  43     BLOCK_REPLICATION_FAILOVER_FAILED,  /* failover failed */
  44     BLOCK_REPLICATION_DONE,             /* block replication is done */
  45 };
  46
  47 static void replication_start(ReplicationState *rs, ReplicationMode mode,
  48                               Error **errp);
  49 static void replication_do_checkpoint(ReplicationState *rs, Error **errp);
  50 static void replication_get_error(ReplicationState *rs, Error **errp);
  51 static void replication_stop(ReplicationState *rs, bool failover,
  52                              Error **errp);
  53
  54 #define REPLICATION_MODE        "mode"
  55 #define REPLICATION_TOP_ID      "top-id"
  56 static QemuOptsList replication_runtime_opts = {
  57     .name = "replication",
  58     .head = QTAILQ_HEAD_INITIALIZER(replication_runtime_opts.head),
  59     .desc = {
  60         {
  61             .name = REPLICATION_MODE,
  62             .type = QEMU_OPT_STRING,
  63         },
  64         {
  65             .name = REPLICATION_TOP_ID,
  66             .type = QEMU_OPT_STRING,
  67         },
  68         { /* end of list */ }
  69     },
  70 };
  71
  72 static ReplicationOps replication_ops = {
  73     .start = replication_start,
  74     .checkpoint = replication_do_checkpoint,
  75     .get_error = replication_get_error,
  76     .stop = replication_stop,
  77 };
  78
  79 static int replication_open(BlockDriverState *bs, QDict *options,
  80                             int flags, Error **errp)
  81 {
  82     int ret;
  83     BDRVReplicationState *s = bs->opaque;
  84     Error *local_err = NULL;
  85     QemuOpts *opts = NULL;
  86     const char *mode;
  87     const char *top_id;
  88
  89     ret = -EINVAL;
  90     opts = qemu_opts_create(&replication_runtime_opts, NULL, 0, &error_abort);
  91     qemu_opts_absorb_qdict(opts, options, &local_err);
  92     if (local_err) {
  93         goto fail;
  94     }
  95
  96     mode = qemu_opt_get(opts, REPLICATION_MODE);
  97     if (!mode) {
  98         error_setg(&local_err, "Missing the option mode");
  99         goto fail;
 100     }
 101
 102     if (!strcmp(mode, "primary")) {
 103         s->mode = REPLICATION_MODE_PRIMARY;
 104         top_id = qemu_opt_get(opts, REPLICATION_TOP_ID);
 105         if (top_id) {
 106             error_setg(&local_err, "The primary side does not support option top-id");
 107             goto fail;
 108         }
 109     } else if (!strcmp(mode, "secondary")) {
 110         s->mode = REPLICATION_MODE_SECONDARY;
 111         top_id = qemu_opt_get(opts, REPLICATION_TOP_ID);
 112         s->top_id = g_strdup(top_id);
 113         if (!s->top_id) {
 114             error_setg(&local_err, "Missing the option top-id");
 115             goto fail;
 116         }
 117     } else {
 118         error_setg(&local_err,
 119                    "The option mode's value should be primary or secondary");
 120         goto fail;
 121     }
 122
 123     s->rs = replication_new(bs, &replication_ops);
 124
 125     ret = 0;
 126
 127 fail:
 128     qemu_opts_del(opts);
 129     error_propagate(errp, local_err);
 130
 131     return ret;
 132 }
 133
 134 static void replication_close(BlockDriverState *bs)
 135 {
 136     BDRVReplicationState *s = bs->opaque;
 137
 138     if (s->replication_state == BLOCK_REPLICATION_RUNNING) {
 139         replication_stop(s->rs, false, NULL);
 140     }
 141     if (s->replication_state == BLOCK_REPLICATION_FAILOVER) {
 142         block_job_cancel_sync(s->active_disk->bs->job);
 143     }
 144
 145     if (s->mode == REPLICATION_MODE_SECONDARY) {
 146         g_free(s->top_id);
 147     }
 148
 149     replication_remove(s->rs);
 150 }
 151
 152 static int64_t replication_getlength(BlockDriverState *bs)
 153 {
 154     return bdrv_getlength(bs->file->bs);
 155 }
 156
 157 static int replication_get_io_status(BDRVReplicationState *s)
 158 {
 159     switch (s->replication_state) {
 160     case BLOCK_REPLICATION_NONE:
 161         return -EIO;
 162     case BLOCK_REPLICATION_RUNNING:
 163         return 0;
 164     case BLOCK_REPLICATION_FAILOVER:
 165         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
 166     case BLOCK_REPLICATION_FAILOVER_FAILED:
 167         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 1;
 168     case BLOCK_REPLICATION_DONE:
 169         /*
 170          * active commit job completes, and active disk and secondary_disk
 171          * is swapped, so we can operate bs->file directly
 172          */
 173         return s->mode == REPLICATION_MODE_PRIMARY ? -EIO : 0;
 174     default:
 175         abort();
 176     }
 177 }
 178
 179 static int replication_return_value(BDRVReplicationState *s, int ret)
 180 {
 181     if (s->mode == REPLICATION_MODE_SECONDARY) {
 182         return ret;
 183     }
 184
 185     if (ret < 0) {
 186         s->error = ret;
 187         ret = 0;
 188     }
 189
 190     return ret;
 191 }
 192
 193 static coroutine_fn int replication_co_readv(BlockDriverState *bs,
 194                                              int64_t sector_num,
 195                                              int remaining_sectors,
 196                                              QEMUIOVector *qiov)
 197 {
 198     BDRVReplicationState *s = bs->opaque;
 199     BdrvChild *child = s->secondary_disk;
 200     BlockJob *job = NULL;
 201     CowRequest req;
 202     int ret;
 203
 204     if (s->mode == REPLICATION_MODE_PRIMARY) {
 205         /* We only use it to forward primary write requests */
 206         return -EIO;
 207     }
 208
 209     ret = replication_get_io_status(s);
 210     if (ret < 0) {
 211         return ret;
 212     }
 213
 214     if (child && child->bs) {
 215         job = child->bs->job;
 216     }
 217
 218     if (job) {
 219         backup_wait_for_overlapping_requests(child->bs->job, sector_num,
 220                                              remaining_sectors);
 221         backup_cow_request_begin(&req, child->bs->job, sector_num,
 222                                  remaining_sectors);
 223         ret = bdrv_co_readv(bs->file, sector_num, remaining_sectors,
 224                             qiov);
 225         backup_cow_request_end(&req);
 226         goto out;
 227     }
 228
 229     ret = bdrv_co_readv(bs->file, sector_num, remaining_sectors, qiov);
 230 out:
 231     return replication_return_value(s, ret);
 232 }
 233
 234 static coroutine_fn int replication_co_writev(BlockDriverState *bs,
 235                                               int64_t sector_num,
 236                                               int remaining_sectors,
 237                                               QEMUIOVector *qiov)
 238 {
 239     BDRVReplicationState *s = bs->opaque;
 240     QEMUIOVector hd_qiov;
 241     uint64_t bytes_done = 0;
 242     BdrvChild *top = bs->file;
 243     BdrvChild *base = s->secondary_disk;
 244     BdrvChild *target;
 245     int ret, n;
 246
 247     ret = replication_get_io_status(s);
 248     if (ret < 0) {
 249         goto out;
 250     }
 251
 252     if (ret == 0) {
 253         ret = bdrv_co_writev(top, sector_num,
 254                              remaining_sectors, qiov);
 255         return replication_return_value(s, ret);
 256     }
 257
 258     /*
 259      * Failover failed, only write to active disk if the sectors
 260      * have already been allocated in active disk/hidden disk.
 261      */
 262     qemu_iovec_init(&hd_qiov, qiov->niov);
 263     while (remaining_sectors > 0) {
 264         ret = bdrv_is_allocated_above(top->bs, base->bs, sector_num,
 265                                       remaining_sectors, &n);
 266         if (ret < 0) {
 267             goto out1;
 268         }
 269
 270         qemu_iovec_reset(&hd_qiov);
 271         qemu_iovec_concat(&hd_qiov, qiov, bytes_done, n * BDRV_SECTOR_SIZE);
 272
 273         target = ret ? top : base;
 274         ret = bdrv_co_writev(target, sector_num, n, &hd_qiov);
 275         if (ret < 0) {
 276             goto out1;
 277         }
 278
 279         remaining_sectors -= n;
 280         sector_num += n;
 281         bytes_done += n * BDRV_SECTOR_SIZE;
 282     }
 283
 284 out1:
 285     qemu_iovec_destroy(&hd_qiov);
 286 out:
 287     return ret;
 288 }
 289
 290 static bool replication_recurse_is_first_non_filter(BlockDriverState *bs,
 291                                                     BlockDriverState *candidate)
 292 {
 293     return bdrv_recurse_is_first_non_filter(bs->file->bs, candidate);
 294 }
 295
 296 static void secondary_do_checkpoint(BDRVReplicationState *s, Error **errp)
 297 {
 298     Error *local_err = NULL;
 299     int ret;
 300
 301     if (!s->secondary_disk->bs->job) {
 302         error_setg(errp, "Backup job was cancelled unexpectedly");
 303         return;
 304     }
 305
 306     backup_do_checkpoint(s->secondary_disk->bs->job, &local_err);
 307     if (local_err) {
 308         error_propagate(errp, local_err);
 309         return;
 310     }
 311
 312     ret = s->active_disk->bs->drv->bdrv_make_empty(s->active_disk->bs);
 313     if (ret < 0) {
 314         error_setg(errp, "Cannot make active disk empty");
 315         return;
 316     }
 317
 318     ret = s->hidden_disk->bs->drv->bdrv_make_empty(s->hidden_disk->bs);
 319     if (ret < 0) {
 320         error_setg(errp, "Cannot make hidden disk empty");
 321         return;
 322     }
 323 }
 324
 325 static void reopen_backing_file(BlockDriverState *bs, bool writable,
 326                                 Error **errp)
 327 {
 328     BDRVReplicationState *s = bs->opaque;
 329     BlockReopenQueue *reopen_queue = NULL;
 330     int orig_hidden_flags, orig_secondary_flags;
 331     int new_hidden_flags, new_secondary_flags;
 332     Error *local_err = NULL;
 333
 334     if (writable) {
 335         orig_hidden_flags = s->orig_hidden_flags =
 336                                 bdrv_get_flags(s->hidden_disk->bs);
 337         new_hidden_flags = (orig_hidden_flags | BDRV_O_RDWR) &
 338                                                     ~BDRV_O_INACTIVE;
 339         orig_secondary_flags = s->orig_secondary_flags =
 340                                 bdrv_get_flags(s->secondary_disk->bs);
 341         new_secondary_flags = (orig_secondary_flags | BDRV_O_RDWR) &
 342                                                      ~BDRV_O_INACTIVE;
 343     } else {
 344         orig_hidden_flags = (s->orig_hidden_flags | BDRV_O_RDWR) &
 345                                                     ~BDRV_O_INACTIVE;
 346         new_hidden_flags = s->orig_hidden_flags;
 347         orig_secondary_flags = (s->orig_secondary_flags | BDRV_O_RDWR) &
 348                                                     ~BDRV_O_INACTIVE;
 349         new_secondary_flags = s->orig_secondary_flags;
 350     }
 351
 352     if (orig_hidden_flags != new_hidden_flags) {
 353         reopen_queue = bdrv_reopen_queue(reopen_queue, s->hidden_disk->bs, NULL,
 354                                          new_hidden_flags);
 355     }
 356
 357     if (!(orig_secondary_flags & BDRV_O_RDWR)) {
 358         reopen_queue = bdrv_reopen_queue(reopen_queue, s->secondary_disk->bs,
 359                                          NULL, new_secondary_flags);
 360     }
 361
 362     if (reopen_queue) {
 363         bdrv_reopen_multiple(bdrv_get_aio_context(bs),
 364                              reopen_queue, &local_err);
 365         error_propagate(errp, local_err);
 366     }
 367 }
 368
 369 static void backup_job_cleanup(BlockDriverState *bs)
 370 {
 371     BDRVReplicationState *s = bs->opaque;
 372     BlockDriverState *top_bs;
 373
 374     top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
 375     if (!top_bs) {
 376         return;
 377     }
 378     bdrv_op_unblock_all(top_bs, s->blocker);
 379     error_free(s->blocker);
 380     reopen_backing_file(bs, false, NULL);
 381 }
 382
 383 static void backup_job_completed(void *opaque, int ret)
 384 {
 385     BlockDriverState *bs = opaque;
 386     BDRVReplicationState *s = bs->opaque;
 387
 388     if (s->replication_state != BLOCK_REPLICATION_FAILOVER) {
 389         /* The backup job is cancelled unexpectedly */
 390         s->error = -EIO;
 391     }
 392
 393     backup_job_cleanup(bs);
 394 }
 395
 396 static bool check_top_bs(BlockDriverState *top_bs, BlockDriverState *bs)
 397 {
 398     BdrvChild *child;
 399
 400     /* The bs itself is the top_bs */
 401     if (top_bs == bs) {
 402         return true;
 403     }
 404
 405     /* Iterate over top_bs's children */
 406     QLIST_FOREACH(child, &top_bs->children, next) {
 407         if (child->bs == bs || check_top_bs(child->bs, bs)) {
 408             return true;
 409         }
 410     }
 411
 412     return false;
 413 }
 414
 415 static void replication_start(ReplicationState *rs, ReplicationMode mode,
 416                               Error **errp)
 417 {
 418     BlockDriverState *bs = rs->opaque;
 419     BDRVReplicationState *s;
 420     BlockDriverState *top_bs;
 421     int64_t active_length, hidden_length, disk_length;
 422     AioContext *aio_context;
 423     Error *local_err = NULL;
 424     BlockJob *job;
 425
 426     aio_context = bdrv_get_aio_context(bs);
 427     aio_context_acquire(aio_context);
 428     s = bs->opaque;
 429
 430     if (s->replication_state != BLOCK_REPLICATION_NONE) {
 431         error_setg(errp, "Block replication is running or done");
 432         aio_context_release(aio_context);
 433         return;
 434     }
 435
 436     if (s->mode != mode) {
 437         error_setg(errp, "The parameter mode's value is invalid, needs %d,"
 438                    " but got %d", s->mode, mode);
 439         aio_context_release(aio_context);
 440         return;
 441     }
 442
 443     switch (s->mode) {
 444     case REPLICATION_MODE_PRIMARY:
 445         break;
 446     case REPLICATION_MODE_SECONDARY:
 447         s->active_disk = bs->file;
 448         if (!s->active_disk || !s->active_disk->bs ||
 449                                     !s->active_disk->bs->backing) {
 450             error_setg(errp, "Active disk doesn't have backing file");
 451             aio_context_release(aio_context);
 452             return;
 453         }
 454
 455         s->hidden_disk = s->active_disk->bs->backing;
 456         if (!s->hidden_disk->bs || !s->hidden_disk->bs->backing) {
 457             error_setg(errp, "Hidden disk doesn't have backing file");
 458             aio_context_release(aio_context);
 459             return;
 460         }
 461
 462         s->secondary_disk = s->hidden_disk->bs->backing;
 463         if (!s->secondary_disk->bs || !bdrv_has_blk(s->secondary_disk->bs)) {
 464             error_setg(errp, "The secondary disk doesn't have block backend");
 465             aio_context_release(aio_context);
 466             return;
 467         }
 468
 469         /* verify the length */
 470         active_length = bdrv_getlength(s->active_disk->bs);
 471         hidden_length = bdrv_getlength(s->hidden_disk->bs);
 472         disk_length = bdrv_getlength(s->secondary_disk->bs);
 473         if (active_length < 0 || hidden_length < 0 || disk_length < 0 ||
 474             active_length != hidden_length || hidden_length != disk_length) {
 475             error_setg(errp, "Active disk, hidden disk, secondary disk's length"
 476                        " are not the same");
 477             aio_context_release(aio_context);
 478             return;
 479         }
 480
 481         if (!s->active_disk->bs->drv->bdrv_make_empty ||
 482             !s->hidden_disk->bs->drv->bdrv_make_empty) {
 483             error_setg(errp,
 484                        "Active disk or hidden disk doesn't support make_empty");
 485             aio_context_release(aio_context);
 486             return;
 487         }
 488
 489         /* reopen the backing file in r/w mode */
 490         reopen_backing_file(bs, true, &local_err);
 491         if (local_err) {
 492             error_propagate(errp, local_err);
 493             aio_context_release(aio_context);
 494             return;
 495         }
 496
 497         /* start backup job now */
 498         error_setg(&s->blocker,
 499                    "Block device is in use by internal backup job");
 500
 501         top_bs = bdrv_lookup_bs(s->top_id, s->top_id, NULL);
 502         if (!top_bs || !bdrv_is_root_node(top_bs) ||
 503             !check_top_bs(top_bs, bs)) {
 504             error_setg(errp, "No top_bs or it is invalid");
 505             reopen_backing_file(bs, false, NULL);
 506             aio_context_release(aio_context);
 507             return;
 508         }
 509         bdrv_op_block_all(top_bs, s->blocker);
 510         bdrv_op_unblock(top_bs, BLOCK_OP_TYPE_DATAPLANE, s->blocker);
 511
 512         job = backup_job_create(NULL, s->secondary_disk->bs, s->hidden_disk->bs,
 513                                 0, MIRROR_SYNC_MODE_NONE, NULL, false,
 514                                 BLOCKDEV_ON_ERROR_REPORT,
 515                                 BLOCKDEV_ON_ERROR_REPORT, BLOCK_JOB_INTERNAL,
 516                                 backup_job_completed, bs, NULL, &local_err);
 517         if (local_err) {
 518             error_propagate(errp, local_err);
 519             backup_job_cleanup(bs);
 520             aio_context_release(aio_context);
 521             return;
 522         }
 523         block_job_start(job);
 524         break;
 525     default:
 526         aio_context_release(aio_context);
 527         abort();
 528     }
 529
 530     s->replication_state = BLOCK_REPLICATION_RUNNING;
 531
 532     if (s->mode == REPLICATION_MODE_SECONDARY) {
 533         secondary_do_checkpoint(s, errp);
 534     }
 535
 536     s->error = 0;
 537     aio_context_release(aio_context);
 538 }
 539
 540 static void replication_do_checkpoint(ReplicationState *rs, Error **errp)
 541 {
 542     BlockDriverState *bs = rs->opaque;
 543     BDRVReplicationState *s;
 544     AioContext *aio_context;
 545
 546     aio_context = bdrv_get_aio_context(bs);
 547     aio_context_acquire(aio_context);
 548     s = bs->opaque;
 549
 550     if (s->mode == REPLICATION_MODE_SECONDARY) {
 551         secondary_do_checkpoint(s, errp);
 552     }
 553     aio_context_release(aio_context);
 554 }
 555
 556 static void replication_get_error(ReplicationState *rs, Error **errp)
 557 {
 558     BlockDriverState *bs = rs->opaque;
 559     BDRVReplicationState *s;
 560     AioContext *aio_context;
 561
 562     aio_context = bdrv_get_aio_context(bs);
 563     aio_context_acquire(aio_context);
 564     s = bs->opaque;
 565
 566     if (s->replication_state != BLOCK_REPLICATION_RUNNING) {
 567         error_setg(errp, "Block replication is not running");
 568         aio_context_release(aio_context);
 569         return;
 570     }
 571
 572     if (s->error) {
 573         error_setg(errp, "I/O error occurred");
 574         aio_context_release(aio_context);
 575         return;
 576     }
 577     aio_context_release(aio_context);
 578 }
 579
 580 static void replication_done(void *opaque, int ret)
 581 {
 582     BlockDriverState *bs = opaque;
 583     BDRVReplicationState *s = bs->opaque;
 584
 585     if (ret == 0) {
 586         s->replication_state = BLOCK_REPLICATION_DONE;
 587
 588         /* refresh top bs's filename */
 589         bdrv_refresh_filename(bs);
 590         s->active_disk = NULL;
 591         s->secondary_disk = NULL;
 592         s->hidden_disk = NULL;
 593         s->error = 0;
 594     } else {
 595         s->replication_state = BLOCK_REPLICATION_FAILOVER_FAILED;
 596         s->error = -EIO;
 597     }
 598 }
 599
 600 static void replication_stop(ReplicationState *rs, bool failover, Error **errp)
 601 {
 602     BlockDriverState *bs = rs->opaque;
 603     BDRVReplicationState *s;
 604     AioContext *aio_context;
 605
 606     aio_context = bdrv_get_aio_context(bs);
 607     aio_context_acquire(aio_context);
 608     s = bs->opaque;
 609
 610     if (s->replication_state != BLOCK_REPLICATION_RUNNING) {
 611         error_setg(errp, "Block replication is not running");
 612         aio_context_release(aio_context);
 613         return;
 614     }
 615
 616     switch (s->mode) {
 617     case REPLICATION_MODE_PRIMARY:
 618         s->replication_state = BLOCK_REPLICATION_DONE;
 619         s->error = 0;
 620         break;
 621     case REPLICATION_MODE_SECONDARY:
 622         /*
 623          * This BDS will be closed, and the job should be completed
 624          * before the BDS is closed, because we will access hidden
 625          * disk, secondary disk in backup_job_completed().
 626          */
 627         if (s->secondary_disk->bs->job) {
 628             block_job_cancel_sync(s->secondary_disk->bs->job);
 629         }
 630
 631         if (!failover) {
 632             secondary_do_checkpoint(s, errp);
 633             s->replication_state = BLOCK_REPLICATION_DONE;
 634             aio_context_release(aio_context);
 635             return;
 636         }
 637
 638         s->replication_state = BLOCK_REPLICATION_FAILOVER;
 639         commit_active_start(NULL, s->active_disk->bs, s->secondary_disk->bs,
 640                             BLOCK_JOB_INTERNAL, 0, BLOCKDEV_ON_ERROR_REPORT,
 641                             replication_done, bs, errp, true);
 642         break;
 643     default:
 644         aio_context_release(aio_context);
 645         abort();
 646     }
 647     aio_context_release(aio_context);
 648 }
 649
 650 BlockDriver bdrv_replication = {
 651     .format_name                = "replication",
 652     .protocol_name              = "replication",
 653     .instance_size              = sizeof(BDRVReplicationState),
 654
 655     .bdrv_open                  = replication_open,
 656     .bdrv_close                 = replication_close,
 657
 658     .bdrv_getlength             = replication_getlength,
 659     .bdrv_co_readv              = replication_co_readv,
 660     .bdrv_co_writev             = replication_co_writev,
 661
 662     .is_filter                  = true,
 663     .bdrv_recurse_is_first_non_filter = replication_recurse_is_first_non_filter,
 664
 665     .has_variable_length        = true,
 666 };
 667
 668 static void bdrv_replication_init(void)
 669 {
 670     bdrv_register(&bdrv_replication);
 671 }
 672
 673 block_init(bdrv_replication_init);